Canadian Cardiovascular Society/Canadian Cardiovascular Critical Care Society/Canadian Association of Interventional Cardiology Clinical Practice Update on Optimal Post Cardiac Arrest and Refractory Cardiac Arrest Patient Care

Survival to hospital discharge among patients with out-of-hospital cardiac arrest (OHCA) is low and important regional differences in treatment practices and survival have been described. Since the 2017 publication of the Canadian Cardiovascular Society's position statement on OHCA care, multiple randomized controlled trials have helped to better define optimal post cardiac arrest care. This working group provides updated guidance on the timing of cardiac catheterization in patients with ST-elevation and without ST-segment elevation, on a revised temperature control strategy targeting normothermia instead of hypothermia, blood pressure, oxygenation, and ventilation parameters, and on the treatment of rhythmic and periodic electroencephalography patterns in patients with a resuscitated OHCA. In addition, prehospital trials have helped craft new expert opinions on antiarrhythmic strategies (amiodarone or lidocaine) and outline the potential role for double sequential defibrillation in patients with refractory cardiac arrest when equipment and training is available. Finally, we advocate for regionalized OHCA care systems with admissions to a hospital capable of integrating their post OHCA care with comprehensive on-site cardiovascular services and provide guidance on the potential role of extracorporeal cardiopulmonary resuscitation in patients with refractory cardiac arrest. We believe that knowledge translation through national harmonization and adoption of contemporary best practices has the potential to improve survival and functional outcomes in the OHCA population.

Arrhythmic events and mortality in patients with cardiogenic shock on inotropic support: results of the DOREMI randomized trial

BACKGROUND

Inotropic support is widely used in the management of cardiogenic shock (CS). Existing data on the incidence and significance of arrhythmic events in patients with CS on inotropic support is at high risk of bias.

METHODS

The DObutamine compaREd to MIlrinone (DOREMI) trial randomized patients to receive dobutamine or milrinone in a double-blind fashion. Patients with and without arrhythmic events (defined as arrhythmias requiring intervention or sustained ventricular arrhythmias) were compared to (1) identify factors associated with their occurrence and (2) examine their association with in-hospital mortality and secondary outcomes.

RESULTS

Ninety-two patients (47.9%) had arrhythmic events, occurring equally with dobutamine and milrinone (P=0.563). The need for vasopressor support at inotrope initiation and a history of atrial fibrillation were positively associated with arrhythmic events whereas predominant right ventricular dysfunction, previous myocardial infarction, and increasing left ventricular ejection fraction were negatively associated with them. Supraventricular arrhythmic events were not associated with mortality (RR 0.97, 95% CI 0.68-1.40, P=0.879) but were positively associated with resuscitated cardiac arrests and hospital length of stay. Ventricular arrhythmic events were positively associated with mortality (RR 1.66, 95% CI 1.13-2.43; P=0.026) and resuscitated cardiac arrests. Arrhythmic events were most often treated with amiodarone (97%) and electrical cardioversion (27%), which were not associated with mortality.

CONCLUSIONS

Clinically relevant arrhythmic events occur in approximately half of patients with CS treated with dobutamine or milrinone and are associated with adverse clinical outcomes. Five factors may help identify patients most at risk of arrhythmic events.

Modifiable Risk Factors and Residual Risk Following Coronary Revascularization: Insights From a Regionalized Dedicated Follow-Up Clinic

OBJECTIVE

To ensure compliance with optimal secondary prevention strategies and document the residual risk of patients following revascularization, we established a postrevascularization clinic for risk-factor optimization at 1 year, with outcomes recorded in a web-based registry. Although coronary revascularization can reduce ischemia, medical treatment of coronary artery disease (CAD) remains the cornerstone of ongoing risk reduction. While standardized referral pathways and protocols for revascularization are prevalent and well studied, post-revascularization care is often less formalized.

PATIENTS AND METHODS

The University of Ottawa Heart Institute is a tertiary-care center providing coronary revascularization services. From 2015 to 2019, data were prospectively recorded in the CAPITAL revascularization registry, and patient-level procedural, clinical, and outcome data are collected in the year following revascularization. Major adverse cardiovascular event (MACE) was defined as death, myocardial infarction, unplanned revascularization, or cerebrovascular accident. Kaplan-Meier curves were generated to evaluate time-to-event data for clinical outcomes by risk-factor management, and comparisons were performed using log-rank tests and reported by hazard ratio (HR) and 95% confidence intervals (CIs).

RESULTS

A cohort of 4147 patients completed 1-year follow-up after revascularization procedure that included 3462 undergoing percutaneous coronary intervention (PCI), 589 undergoing coronary artery bypass graft (CABG), and 96 undergoing both PCI and CABG. In the year following revascularization (median follow-up 13.3 months-interquartile range [IQR]: 11.9-16.5) 11% of patients experienced MACE, with female patients being disproportionately at risk. Moreover, 47.7% of patients had ≥2 risk factors (diabetes, dyslipidemia, overweight, active smoker) at the time of follow-up, with 45.0% of patients with diabetes failing to achieve target hemoglobin (Hb) A1c, 54.8% of smokers continuing to smoke, and 27.1% of patients failing to achieve guideline-directed lipid targets.

CONCLUSION

Patients who have undergone revascularization procedures remain at elevated risk for MACE, and inadequately controlled risk factors are prevalent in follow-up. This highlights the need for aggressive secondary prevention strategies and implementation of programs to optimize postrevascularization care.

Determinants of long-term dual antiplatelet therapy use in post myocardial infarction patients: Insights from the TIGRIS registry

BACKGROUND

Patterns of dual antiplatelet therapy (DAPT) use beyond 1 year post-myocardial infarction (MI) have not been well studied.

METHODS

TIGRIS (NCT01866904) was a prospective, multi-center (369 centers in 24 countries), observational study of patients 1 to 3 years post-MI. We sought to identify the prevalence and determinants of DAPT use ≥1 year post-MI in patients enrolled in TIGRIS. We used multivariable logistic regression to identify determinants of DAPT use at 396 days post-MI (365 days plus a 31day overrun period to account for intended DAPT discontinuation at 1 year). Patients treated with an oral anticoagulant were excluded.

RESULTS

Of 7708 patients (median age 67 years, women 25%, ST-elevation MI 50%), 39% and 16% were on DAPT at 396 days and 5 years post-MI, respectively. DAPT use at 396 days post-MI was more prevalent in patients <65 years of age, treated with percutaneous coronary intervention (versus coronary artery bypass grafting or medical therapy), and with multivessel disease or a history of angina. Additional clinical determinants of ischemic and/or bleeding events following MI (diabetes, second prior MI, hypertension, peripheral artery disease, heart failure, smoking, and renal insufficiency) were not independently associated with DAPT use at 396 days. There were geographic variations in the use of DAPT at 396 days (p<0.001), with the lowest use in Europe and the highest in Asia and Australia.

CONCLUSION

In a contemporary patient cohort, DAPT use beyond 1 year post MI was prevalent and associated with patient and index event characteristics. There were marked geographical variations in DAPT use beyond 1 year post MI.

Implications of Myocardial Infarction on Management and Outcome in Cardiogenic Shock

Background The randomized DOREMI (Dobutamine Compared to Milrinone) clinical trial evaluated the efficacy and safety of milrinone and dobutamine in patients with cardiogenic shock. Whether the results remain consistent when stratified by acute myocardial infarction remains unknown. In this substudy, we sought to evaluate differences in clinical management and outcomes of acute myocardial infarction complicated by cardiogenic shock (AMICS) versus non-AMICS. Methods and Results Patients in cardiogenic shock (n=192) were randomized 1:1 to dobutamine or milrinone. The primary composite end point in this subgroup analysis was all-cause in-hospital mortality, cardiac arrest, non-fatal myocardial infarction, cerebrovascular accident, the need for mechanical circulatory support, or initiation of renal replacement therapy (RRT) at 30-days. Outcomes were evaluated in patients with (n=65) and without (n=127) AMICS. The primary composite end point was significantly higher in AMICS versus non-AMICS (hazard ratio [HR], 2.21; 95% CI, 1.47-3.30; P=0.0001). The primary end point was driven by increased rates of all-cause mortality, mechanical circulatory support, and RRT. No differences in other secondary outcomes including cardiac arrest or cerebrovascular accident were observed. AMICS remained associated with the primary composite outcome, 30-day mortality, and RRT after adjustment for age, sex, procedural contrast use, multivessel disease, and inotrope type. Conclusions AMI was associated with increased rates of adverse clinical outcomes in cardiogenic shock along with increased rates of mortality and initiation of mechanical circulatory support and RRT. Contrast administration during revascularization likely contributes to increased rates of RRT. Heterogeneity of outcomes in AMICS versus non-AMICS highlights the need to study interventions in specific subgroups of cardiogenic shock. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03207165.

Outcomes of retrograde approach for chronic total occlusions by guidewire location

BACKGROUND

Connecting the antegrade wire (AW) and the retrograde wire (RW) is a goal of chronic total occlusion (CTO) treatment, but angiographic guidewire location is sometimes misleading.

AIMS

The aim of this study was to evaluate the association between intravascular ultrasound (IVUS)-defined AW and RW position and procedural outcomes when treating CTO lesions using the retrograde approach.

METHODS

Overall, 191 CTO lesions treated using an IVUS-guided retrograde approach at three centres in Japan, China, and the USA were included.

RESULTS

When the AW and RW angiographically overlapped, four wire positions were seen on IVUS: (i) AW within the plaque (AW-intraplaque) and RW-intraplaque in 34%; (ii) AW-intraplaque and RW in the subintimal space (RW-subintima) in 28%; (iii) AW-subintima and RW-subintima in 22%; or (iv) AW-subintima and RW-intraplaque in 16%. The procedure succeeded without repositioning the wire in 89% of AW-intraplaque/RW-intraplaque, 61% of AW-intraplaque/RW-subintima and 57% of AW-subintima/RW-subintima, but only one (3%) AW-subintima/RW-intraplaque. Lesion and procedure complexity and failure/complications were greatest in AW-subintima/RW-intraplaque.

CONCLUSIONS

IVUS-identified vascular compartment concordance versus IVUS-identified vascular compartment mismatch leads to higher success rates irrespective of intraplaque or subintimal passage. AW-subintima/RW-intraplaque was associated with the most complex CTO morphology and procedure, and repositioning the wire was almost always necessary. Visual summary. When the antegrade wire is in the subintimal space and the retrograde wire is in the intraplaque, re-wiring is almost always necessary.

The association between mean arterial pressure and outcomes in patients with cardiogenic shock: insights from the DOREMI trial

AIMS

Cardiogenic shock (CS) is a state of low cardiac output resulting in end-organ hypoperfusion. Despite high in-hospital mortality rates, little evidence exists regarding the optimal mean arterial pressure (MAP) target in CS. We therefore evaluated the relationship between achieved MAP and clinical outcomes in patients with CS.

METHODS AND RESULTS

We performed a post hoc analysis of the CAPITAL DOREMI trial: a randomized, double-blind trial comparing dobutamine to milrinone in patients with CS. We divided patients into a high MAP group (average MAP ≥ 70 mmHg over the 36 h following randomization), and a low MAP group (average MAP < 70 mmHg). Our primary outcome included in-hospital all-cause mortality, resuscitated cardiac arrest, need for cardiac transplantation or mechanical circulatory support, non-fatal myocardial infarction, transient ischaemic attack or stroke, or initiation of renal replacement therapy. In total, 71 (37.0%) patients achieved an average MAP < 70 mmHg, and 121 (63.0%) achieved an average MAP ≥ 70 mmHg. The primary outcome occurred in 48 (67.6%) patients in the low MAP group and 51 (42.2%) patients in the high MAP group [adjusted relative risk (aRR) 0.70; 95% confidence interval (CI) 0.53-0.92; P = 0.01]. All-cause mortality occurred in 41 (57.8%) and 35 (28.9%) patients in the low and high MAP groups, respectively (aRR 0.56; 95% CI 0.40-0.79; P < 0.01). There were no significant differences in any secondary outcomes between each group.

CONCLUSIONS

In patients with CS treated with inotrope therapy, low MAP is associated with worse clinical outcomes. Randomized data evaluating optimal MAP targets in CS is needed to guide medical therapy.

Impact of baseline beta-blocker use on inotrope response and clinical outcomes in cardiogenic shock: a subgroup analysis of the DOREMI trial

Background

Cardiogenic shock (CS) is associated with significant morbidity and mortality. The impact of beta-blocker (BB) use on patients who develop CS remains unknown. We sought to evaluate the clinical outcomes and hemodynamic response profiles in patients treated with BB in the 24 h prior to the development of CS.

Methods

Patients with CS enrolled in the DObutamine compaREd to MIlrinone trial were analyzed. The primary outcome was a composite of all-cause mortality, resuscitated cardiac arrest, need for cardiac transplant or mechanical circulatory support, non-fatal myocardial infarction, transient ischemic attack or stroke, or initiation of renal replacement therapy. Secondary outcomes included the individual components of the primary composite and hemodynamic response profiles derived from pulmonary artery catheters.

Results

Among 192 participants, 93 patients (48%) had received BB therapy. The primary outcome occurred in 47 patients (51%) in the BB group and in 52 (53%) in the no BB group (RR 0.96; 95% CI 0.73–1.27; P = 0.78) throughout the in-hospital period. There were fewer early deaths in the BB group (RR 0.41; 95% CI 0.18–0.95; P = 0.03). There were no differences in other individual components of the primary outcome or in hemodynamic response between the two groups throughout the remainder of the hospitalization.

Conclusions

BB therapy in the 24 h preceding the development of CS did not negatively influence clinical outcomes or hemodynamic parameters. On the contrary, BB use was associated with fewer deaths in the early resuscitation period, suggesting a paradoxically protective effect in patients with CS.

Trial registration ClinicalTrials.gov Identifier: NCT03207165

Milrinone as Compared with Dobutamine in the Treatment of Cardiogenic Shock

BACKGROUND

Cardiogenic shock is associated with substantial morbidity and mortality. Although inotropic support is a mainstay of medical therapy for cardiogenic shock, little evidence exists to guide the selection of inotropic agents in clinical practice.

METHODS

We randomly assigned patients with cardiogenic shock to receive milrinone or dobutamine in a double-blind fashion. The primary outcome was a composite of in-hospital death from any cause, resuscitated cardiac arrest, receipt of a cardiac transplant or mechanical circulatory support, nonfatal myocardial infarction, transient ischemic attack or stroke diagnosed by a neurologist, or initiation of renal replacement therapy. Secondary outcomes included the individual components of the primary composite outcome.

RESULTS

A total of 192 participants (96 in each group) were enrolled. The treatment groups did not differ significantly with respect to the primary outcome; a primary outcome event occurred in 47 participants (49%) in the milrinone group and in 52 participants (54%) in the dobutamine group (relative risk, 0.90; 95% confidence interval [CI], 0.69 to 1.19; P = 0.47). There were also no significant differences between the groups with respect to secondary outcomes, including in-hospital death (37% and 43% of the participants, respectively; relative risk, 0.85; 95% CI, 0.60 to 1.21), resuscitated cardiac arrest (7% and 9%; hazard ratio, 0.78; 95% CI, 0.29 to 2.07), receipt of mechanical circulatory support (12% and 15%; hazard ratio, 0.78; 95% CI, 0.36 to 1.71), or initiation of renal replacement therapy (22% and 17%; hazard ratio, 1.39; 95% CI, 0.73 to 2.67).

CONCLUSIONS

In patients with cardiogenic shock, no significant difference between milrinone and dobutamine was found with respect to the primary composite outcome or important secondary outcomes. (Funded by the Innovation Fund of the Alternative Funding Plan for the Academic Health Sciences Centres of Ontario; ClinicalTrials.gov number, NCT03207165.).

Outcomes of retrograde chronic total occlusion percutaneous coronary intervention: A report from the OPEN-CTO registry

OBJECTIVES

We sought to assess in-hospital and long-term outcomes of retrograde compared with antegrade-only percutaneous coronary intervention for chronic total occlusion (CTO PCI).

BACKGROUND

Procedural and clinical outcomes following retrograde compared with antegrade-only CTO PCI remain unknown.

METHODS

Using the core-lab adjudicated OPEN-CTO registry, we compared the outcomes of retrograde to antegrade-only CTO PCI. Primary endpoints included were in-hospital major adverse cardiac and cerebrovascular events (MACCE) (all-cause death, stroke, myocardial infarction [MI], emergency cardiac surgery, or clinically significant perforation) and MACCE at 1-year (all-cause death, MI, stroke, target lesion revascularization, or target vessel reocclusion).

RESULTS

Among 885 single CTO procedures from the OPEN-CTO registry, 454 were retrograde and 431 were antegrade-only. Lesion complexity was higher (J-CTO score: 2.7 vs. 1.9; p < .001) and technical success lower (82.4 vs. 94.2%; p < .001) in retrograde compared with antegrade-only procedures. All-cause death was higher in the retrograde group in-hospital (2 vs. 0%; p = .003), but not at 1-year (4.9 vs. 3.3%; p = .29). Compared with antegrade-only procedures, in-hospital MACCE rates (composite of all-cause death, stroke, MI, emergency cardiac surgery, and clinically significant perforation) were higher in the retrograde group (10.8 vs. 3.3%; p < .001) and at 1-year (19.5 vs. 13.9%; p = .03). In sensitivity analyses landmarked at discharge, there was no difference in MACCE rates at 1 year following retrograde versus antegrade-only CTO PCI. Improvements in Seattle Angina Questionnaire Quality of Life scores at 1-year were similar between the retrograde and antegrade-only groups (29.9 vs 30.4; p = .58).

CONCLUSIONS

In the OPEN-CTO registry, retrograde CTO procedures were associated with higher rates of in-hospital MACCE compared with antegrade-only; however, post-discharge outcomes, including quality of life improvements, were similar between technical modalities.

Revisiting the Evidence for Dipyridamole in Reducing Restenosis: A Systematic Review and Meta-analysis

ABSTRACT

Atherosclerosis remains a leading cause of morbidity and mortality, with revascularization remaining a cornerstone of management. Conventional revascularization modalities remain challenged by target vessel reocclusion-an event driven by mechanical, thrombotic, and proliferative processes. Despite considerable advancements, restenosis remains the focus of ongoing research. Adjunctive agents, including dipyridamole, offer a multitude of effects that may improve vascular homeostasis. We sought to quantify the potential therapeutic impact of dipyridamole on vascular occlusion. We performed a literature search (EMBASE and MEDLINE) examining studies that encompassed 3 areas: (1) one of the designated medical therapies applied in (2) the setting of a vascular intervention with (3) an outcome including vascular occlusion rates and/or quantification of neointimal proliferation/restenosis. The primary outcome was vascular occlusion rates. The secondary outcome was the degree of restenosis by neointimal quantification. Both human and animal studies were included in this translational analysis. There were 6,839 articles screened, from which 73 studies were included, encompassing 16,146 vessels followed up for a mean of 327.3 days (range 7-3650 days). Preclinical studies demonstrate that dipyridamole results in reduced vascular occlusion rates {24.9% vs. 48.8%, risk ratio 0.53 [95% confidence interval (CI) 0.40-0.70], I2 = 39%, P < 0.00001}, owing to diminished neointimal proliferation [standardized mean differences -1.13 (95% CI -1.74 to -0.53), I2 = 91%, P = 0.0002]. Clinical studies similarly demonstrated reduced occlusion rates with dipyridamole therapy [23.5% vs. 31.0%, risk ratio 0.77 (95% CI 0.67-0.88), I2 = 84%, P < 0.0001]. Dipyridamole may improve post-intervention vascular patency and mitigate restenosis. Dedicated studies are warranted to delineate its role as an adjunctive agent after revascularization.

Transradial Versus Transfemoral Access for Percutaneous Coronary Intervention in ST-Segment-Elevation Myocardial Infarction: A Systematic Review and Meta-Analysis

[Figure: see text].

Performance of Plasma Adenosine as a Biomarker for Predicting Cardiovascular Risk

Adenosine boasts promising preclinical and clinical data supporting a vital role in modulating vascular homeostasis. Its widespread use as a diagnostic and therapeutic agent have been limited by its short half-life and complex biology, though adenosine-modulators have shown promise in improving vascular healing. Moreover, circulating adenosine has shown promise in predicting cardiovascular (CV) events. We sought to delineate whether circulating plasma adenosine levels predict CV events in patients undergoing invasive assessment for coronary artery disease. Patients undergoing invasive angiography had clinical data prospectively recorded in the Cardiovascular and Percutaneous ClInical TriALs (CAPITAL) revascularization registry and blood samples collected in the CAPITAL Biobank from which adenosine levels were quantified. Tertile-based analysis was used to assess prediction of major adverse cardiovascular events (MACE; composite of death, myocardial infarction, unplanned revascularization, and cerebrovascular accident). Secondary analyses included MACE subgroups, clinical subgroups and adenosine levels. There were 1,815 patients undergoing angiography who had blood collected with adenosine quantified in 1,323. Of those quantified, 51.0% were revascularized and 7.3% experienced MACE in 12 months of follow-up. Tertile-based analysis failed to demonstrate any stratification of MACE rates (log rank, P = 0.83), when comparing low-to-middle (hazard ratio (HR) 1.10, 95% confidence interval (CI) 0.68-1.78, P = 0.70) or low-to-high adenosine tertiles (HR 0.95, 95% CI 0.56-1.57, P = 0.84). In adjusted analysis, adenosine similarly failed to predict MACE. Finally, adenosine did not predict outcomes in patients with acute coronary syndrome nor in those revascularized or treated medically. Plasma adenosine levels do not predict subsequent CV outcomes or aid in patient risk stratification.

Abstract 125: Capital Do-Re-Mi: A Randomized Trial of Dobutamine Compared to Milrinone in Cardiogenic Shock

Introduction: Cardiogenic shock (CS) is associated with significant morbidity and mortality. Although inotropic support is a mainstay of medical therapy for CS, little evidence exists to guide the selection of inotropic agents in clinical practice.

Methods: In this double blind randomized controlled trial, we assigned patients with SCAI class B to E shock to either milrinone or dobutamine for inotropic support. Therapy was titrated based on clinical, biochemical and hemodynamic response as evaluated by the treating physician. The primary outcome was a combined endpoint of in hospital mortality, non-fatal MI, stroke, new initiation of renal replacement therapy (RRT), need for MCS or cardiac transplant, or cardiac arrest with successful resuscitation. Secondary outcomes included individual components of the primary outcome.

Results: Among 192 participants, there was no significant difference in the primary outcome, occurring in 49% (47 of 96) of patients in the milrinone arm and 54% (52 of 96) patients in the dobutamine group (RR 0.90, 95% CI of 0.69-1.19, p-value = 0.47). There were also no differences in important secondary outcomes between milrinone and dobutamine, including in-hospital mortality 37% (35 of 96) vs 43% (41 of 96) (RR 0.85, 95% CI 0.60-1.21, p-value = 0.38) or need for RRT 22% (21 of 96) vs 17% (16 of 96) (RR 1.31, 95% CI 0.73-2.36, p-value = 0.36).

Conclusions: In this randomized clinical trial of milrinone and dobutamine in CS, there was no difference in the primary composite outcome or in important secondary outcomes. The selection of inotropic agent could reasonably be based on physician comfort, cost and individual response to therapy.

Contrast-free optical coherence tomography:Systematic evaluation of non-contrast media for intravascular assessment

Background

Coronary revascularization using imaging guidance is rapidly becoming the standard of care. Intravascular optical coherence tomography uses near-infrared light to obtain high resolution intravascular images. Standard optical coherence tomography imaging technique employs iodinated contrast dye to achieve the required blood clearance during acquisition. We sought to systematically evaluate the technical performance of saline as an alternative to iodinated contrast for intravascular optical coherence tomography assessment.

Methods and results

We performed bench top optical coherence tomography analysis on nylon tubing with sequential contrast/saline dilutions to empirically derive adjustment coefficients. We then applied these coefficients in vivo in an established rabbit abdominal stenting model with both saline and contrast optical coherence tomography imaging. In this model, we assessed the impact of saline on both quantitative and qualitative vessel assessment. Nylon tubing assessment demonstrated a linear relationship between saline and contrast for both area and diameter. We then derived adjustment coefficients, allowing for accurate calculation of area and diameter when converting saline into both contrast and reference dimensions. In vivo studies confirmed reduced area with saline versus contrast [7.43 (5.67–8.36) mm² versus 8.2 (6.34–9.39) mm², p = 0.001] and diameter [3.08 mm versus 3.23 mm, p = 0.001]. Following correction, a strong relationship was achieved in vivo between saline and contrast in both area and diameter without compromising image quality, artefact, or strut assessment.

Conclusion

Saline generates reduced dimensions compared to contrast during intravascular optical coherence tomography imaging. The relationship across physiologic coronary diameters is linear and can be corrected with high fidelity. Saline does not adversely impact image quality, artefact, or strut assessment.

Temporal Trends in Chronic Total Occlusion Percutaneous Coronary Interventions: Insights From the PROGRESS-CTO Registry

BACKGROUND

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has significantly evolved in recent years.

METHODS

We compared the clinical, angiographic, and technical characteristics, as well as procedural outcomes of CTO-PCIs in a multicenter registry between the "early era" (2012-2016) and the "current era" (2017-2019).

RESULTS

Current era patients more often had stage III or IV angina compared with early era patients (71% vs 66%, respectively; P=.03) and were less likely to undergo ad hoc CTO-PCI (13% vs 16%, respectively; P=.04). The J-CTO score was slightly lower in the current era patients vs the early era patients (2.3 ± 1.4 vs 2.5 ± 1.3, respectively; P=.04). Use of antegrade wire escalation increased in the current era (92% vs 83% in the early era patients; P<.001) whereas use of retrograde crossing decreased (29% vs 39% in the early era; P<.001) and antegrade/ dissection re-entry decreased (23% vs 32% in the early era; P<.001). Technical success rates (85% in the current era vs 86% in the early era; P=.69) and procedural success rates (83% in the current era vs 85% in the early era; P=.15) were similar, whereas the incidence of in-hospital major cardiovascular events decreased in the current era (2% vs 3% in the early era; P=.04).

CONCLUSIONS

During recent years, ad hoc CTO-PCI decreased along with decreasing use of retrograde crossing and antegrade dissection and re-entry. Technical and procedural success rates remained stable, whereas the incidence of in-hospital MACE decreased.

Outcomes with retrograde versus antegrade chronic total occlusion revascularization

OBJECTIVES

The aim of the study was to evaluate the outcomes of retrograde versus antegrade approach in chronic total occlusion (CTO) percutaneous coronary intervention (PCI).

BACKGROUND

The retrograde approach has increased the success rate of CTO PCI but has been associated with a higher risk for complications.

METHODS

We conducted a meta-analysis of studies published between 2000 and August 2019 comparing the in-hospital and long-term outcomes with retrograde versus antegrade CTO PCI.

RESULTS

Twelve observational studies (10,240 patients) met our inclusion criteria (retrograde approach 2,789 patients, antegrade approach 7,451 patients). Lesions treated with the retrograde approach had higher J-CTO score (2.8 vs. 1.9, p < .001). Retrograde CTO PCI was associated with a lower success rate (80.9% vs. 87.4%, p < .001). Both approaches had similar in-hospital mortality, urgent revascularization, and cerebrovascular events. Retrograde CTO PCI was associated with higher risk of in-hospital myocardial infarction (MI; odds ratio [OR] 2.37, 95% confidence intervals [CI] 1.7, 3.32, p < .001), urgent pericardiocentesis (OR 2.53, 95% CI 1.41-4.51, p = .002), and contrast-induced nephropathy (OR 2.12, 95% CI 1.47-3.08; p < .001). During a mean follow-up of 48 ± 31 months retrograde crossing had similar mortality (OR 1.79, 95% CI 0.84-3.81, p = .13), but a higher incidence of MI (OR 2.07, 95% CI 1.1-3.88, p = .02), target vessel revascularization (OR 1.92, 95% CI 1.49-2.46, p < .001), and target lesion revascularization (OR 2.08, 95% CI 1.33-3.28, p = .001).

CONCLUSIONS

Compared with antegrade CTO PCI, retrograde CTO PCI is performed in more complex lesions and is associated with a higher risk for acute and long-term adverse events.

P1932Predictors of DAPT use in patients beyond 1 year post myocardial infarction: Insights from the TIGRIS observational study

Background

International guidelines vary in their recommendations for dual antiplatelet therapy (DAPT) use beyond 1 year post-myocardial infarction (MI).

Purpose

To identify predictors of DAPT use in patients ≥1 year post-MI prior to the publication of the DAPT score and the 2017 European Society of Cardiology (ESC) guidelines for DAPT in coronary artery disease.

Methods

TIGRIS (NCT01866904) was a prospective, multi-center (369 centers in 25 countries), observational study of patients 1 to 3 years post-MI between June 2013 and November 2014. We performed a multivariable logistic regression analysis to identify independent predictors of DAPT use at 396 days post-MI (365 + 31 days overrun period to allow intended DAPT discontinuation at 1 year). Patients on oral anticoagulation were excluded.

Results

Of 8464 patients enrolled (mean age 66 years, women 24%, ST-elevation MI 53%), 40% were on DAPT at 396 days post-MI (Figure). In the subset of patients on DAPT at 396 days post-MI, aspirin was combined with clopidogrel in 84%, prasugrel in 12%, and other antiplatelet agents in 4%. DAPT use at 396 days post-MI was independently associated with geographic region, age, PCI for the index MI, and a history of multivessel disease or angina (Table). Several variables included in the DAPT score and ESC guideline recommendations (diabetes, second prior MI, hypertension, peripheral artery disease, heart failure, smoking, and renal insufficiency) were not independent predictors of DAPT use at 396 days.

Independent predictors of DAPT @396 days Variable at enrolment Patients Odds ratio (95% CI) P-value Region: Europe 3813 Reference group 0.01 North America 923 1.65 (0.56, 4.86) Latin America 1084 2.55 (1.19, 5.47) Asia and Australia 2644 3.01 (1.42, 6.36) Age <65 years 3274 1.15 (1.04, 1.28) 0.005 PCI for index MI 6925 2.08 (1.82, 2.38) <0.0001 Multi-vessel disease 5598 1.37 (1.24, 1.52) <0.0001 History of angina 829 1.46 (1.24, 1.71) <0.0001

DAPT use at 396 days post-MI by region

Conclusion

During the study period, DAPT use ≥1 year post-MI was prevalent and appeared to be influenced by regional practices. Further research is needed to determine whether the DAPT score and the 2017 ESC guidelines for dual antiplatelet therapy have changed long-term DAPT use practices.

Acknowledgement/Funding

AstraZeneca AB, Södertälje, Sweden

Evaluation of Plasma Adenosine as a Marker of Cardiovascular Risk: Analytical and Biological Considerations

Background

Adenosine is a ubiquitous regulatory molecule known to modulate signaling in many cells and processes vital to vascular homeostasis. While studies of adenosine receptors have dominated research in the field, quantification of adenosine systemically and locally remains limited owing largely to technical restrictions. Given the potential clinical implications of adenosine biology, there is a need for adequately powered studies examining the role of plasma adenosine in vascular health. We sought to describe the analytical and biological factors that affect quantification of adenosine in humans in a large, real‐world cohort of patients undergoing evaluation for coronary artery disease.

Methods and Results

Between November 2016 and April 2018, we assessed 1141 patients undergoing angiography for evaluation of coronary artery disease. High‐performance liquid chromatography was used for quantification of plasma adenosine concentration, yielding an analytical coefficient of variance (CV_a) of 3.2%, intra‐subject variance (CV_i) 35.8% and inter‐subject variance (CV_g) 56.7%. Traditional cardiovascular risk factors, medications, and clinical presentation had no significant impact on adenosine levels. Conversely, increasing age (P=0.027) and the presence of obstructive coronary artery disease (P=0.026) were associated with lower adenosine levels. Adjusted multivariable analysis supported only age being inversely associated with adenosine levels (P=0.039).

Conclusions

Plasma adenosine is not significantly impacted by traditional cardiovascular risk factors; however, advancing age and presence of obstructive coronary artery disease may be associated with lower adenosine levels. The degree of intra‐ and inter‐subject variance of adenosine has important implications for biomarker use as a prognosticator of cardiovascular outcomes and as an end point in clinical studies.

Sensitivity and specificity of chest imaging for sarcoidosis screening in patients with cardiac presentations

Background

Patients with sarcoidosis can present with cardiac symptoms as the first manifestation of disease in any organ. In these patients, the use of chest imaging modalities may serve as an initial screening tool towards the diagnosis of sarcoidosis through identification of pulmonary/mediastinal involvement; however, the use of chest imaging for this purpose has not been well studied. We assessed the utility of different chest imaging modalities for initial screening for cardiac sarcoidosis (CS).

Methods and Results

All patients were investigated with chest x-ray, chest computed tomography (CT) and/or cardiac/thorax magnetic resonance imaging (MRI). We then used the final diagnosis (CS versus no CS) and adjudicated imaging reports (normal versus abnormal) to calculate the sensitivity and specificity of individual and combinations of chest imaging modalities. We identified 44 patients (mean age 54 (±8) years, 35.4% female) and a diagnosis of CS was made in 18/44 patients (41%). The sensitivity and specificity for screening for sarcoidosis were 35% and 85% for chest x-ray, respectively (AUC 0.60; 95%CI 0.42-0.78; p value=0.27); 94% and 86% for chest CT (AUC 0.90; 95%CI 0.80-1.00; p value <0.001); 100% and 50% for cardiac/thorax MRI (AUC 0.75; 95%CI 0.56-0.94; p value=0.04).

Conclusions

During the initial diagnostic workup of patients with suspected CS, chest x-ray was suboptimal as a screening test. In contrast CT chest and cardiac/thorax MRI had excellent sensitivity. Chest CT has the highest specificity among imaging modalities. Cardiac/thorax MRI or chest CT could be used as an initial screening test, depending on local availability.

Adenosine as a Marker and Mediator of Cardiovascular Homeostasis: A Translational Perspective

Adenosine, a purine nucleoside, is produced broadly and implicated in the homeostasis of many cells and tissues. It signals predominantly via 4 purinergic adenosine receptors (ADORs) - ADORA1, ADORA2A, ADORA2B and ADOosine signaling, both through design as specific ADOR agonists and antagonists and as offtarget effects of existing anti-platelet medications. Despite this, adenosine has yet to be firmly established as either a therapeutic or a prognostic tool in clinical medicine to date. Herein, we provide a bench-to-bedside review of adenosine biology, highlighting the key considerations for further translational development of this proRA3 in addition to non-ADOR mediated effects. Through these signaling mechanisms, adenosine exerts effects on numerous cell types crucial to maintaining vascular homeostasis, especially following vascular injury. Both in vitro and in vivo models have provided considerable insights into adenosine signaling and identified targets for therapeutic intervention. Numerous pharmacologic agents have been developed that modulate adenmising molecule.

Ischemic and bleeding outcomes after coronary artery bypass grafting among patients initially treated with a P2Y12 receptor antagonist for acute coronary syndromes: Insights on timing of discontinuation of ticagrelor and clopidogrel prior to surgery

BACKGROUND

Clinical outcomes in acute coronary syndrome patients treated with P2Y₁₂ inhibitors who require urgent coronary artery bypass grafting (CABG) have not been well studied.

METHODS

We examined clinical outcomes in acute coronary syndrome patients in relation to the timing of CABG following P2Y₁₂ inhibitor discontinuation (<72 h, 72 h to five days, >5 days). The primary ischemic outcome was a composite of death, reinfarction, need for revascularization, or stroke. The primary safety outcome was bleeding of at least moderate severity as defined by a Universal Definition of Perioperative Bleeding class ≥2.

RESULTS

Among 508 patients (95 ticagrelor, 413 clopidogrel), the timing of CABG following P2Y₁₂ inhibitor discontinuation was <72 h in 32.1%, 72 h to five days in 23.2% and >5 days in 44.7%. Compared with CABG within 72 h, CABG 72 h to five days (adjusted odds ratio (OR) 0.35; 95% confidence interval (CI) 0.14-0.85; p=0.02) but not >5 days (adjusted OR 0.62; 95% CI 0.33-1.16; p=0.14) after P2Y₁₂ inhibitor discontinuation was associated with lower odds of the primary ischemic outcome. Compared with CABG within 72 h, CABG 72 h to five days (adjusted OR 0.38; 95% CI 0.22-0.66; p=0.001) and >5 days (adjusted OR 0.33; 95% CI 0.20-0.53; p<0.001) after P2Y₁₂ inhibitor discontinuation were associated with lower rates of Universal Definition of Perioperative Bleeding class ≥2 bleeding.

CONCLUSIONS

CABG within 72 h after P2Y₁₂ inhibitor discontinuation is associated with excess ischemia and bleeding. The rates of ischemic and bleeding events were comparable in patients undergoing CABG 72 h to five days compared with >5 days after P2Y₁₂ inhibitor discontinuation.

Transcatheter Aortic Valve Implantation (TAVI) for Native Aortic Valve Regurgitation - A Systematic Review

BACKGROUND

Transcatheter aortic valve implantation (TAVI) has become the standard of care for management of high-risk patients with aortic stenosis. Limited data is available regarding the performance of TAVI in patients with native aortic valve regurgitation (NAVR).Methods and Results:We performed a systematic review from 2002 to 2016. The primary outcome was device success as per VARC-2 criteria. Secondary endpoints included procedural complications, and 30-day and 1-year mortality rates. A total of 175 patients were included from 31 studies. Device success was reported in 86.3% of patients - with device failure driven by moderate aortic regurgitation (AR ≥3+) and/or need for a second device. Procedural complications were rare, with no procedural deaths, myocardial infarctions or annular ruptures reported. Procedural safety was acceptable with a low 30-day incidence of stroke (1.5%). The 30-day and 1-year overall mortality rates were 9.6% and 20.0% (cardiovascular death, 3.8% and 10.1%, respectively). Patients receiving 2nd-generation valves demonstrated similar safety profiles with greater device success compared with 1st-generation valves (96.2% vs. 78.4%). This was driven by the higher incidence of second-valve implantation (23.4% vs. 1.7%) and significant paravalvular leak (8.3% vs. 0.0%).

CONCLUSIONS

TAVI demonstrates acceptable safety and efficacy in high-risk patients with severe NAVR. Second-generation valves may afford a similar safety profile with improved device success. Dedicated studies are needed to definitively establish the efficacy of TAVI in this population.

Predicting Acute Kidney Injury following Transcatheter Aortic Valve Replacement

Purpose: Acute kidney injury occurs in up to a quarter of patients following transcatheter aortic valve replacement (TAVR) and has been associated with increased short and long-term mortality rates. A variety of patient characteristics predictive of post-TAVR acute kidney injury (AKI) have been identified, however discrepancies among studies exist almost uniformly. We investigated the hypothesis that the change in glomerular filtration rate (ΔGFR) in response to contrast administered during pre-TAVR coronary angiography is predictive of ΔGFR post-TAVR. Methods: The study comprised 195 patients who underwent TAVR at a single center between August 2008 and June 2015 and were prospectively included in the CAPITAL TAVR registry. Multiple linear regression analysis was conducted to estimate the effect of independent variables on the change in renal function post-TAVR. Results: There was no relationship identified between the ΔGFR post-angiogram and the ΔGFR post-TAVR (r=0.043, P=0.582). Multiple linear regression analysis revealed that a significant amount of the change in renal function post-TAVR can be explained by the patient’s baseline creatinine (beta coefficient, -0.310, P

Does renal function affect the efficacy or safety of a pharmacoinvasive strategy in patients with ST-elevation myocardial infarction? A meta-analysis

BACKGROUND

The efficacy and safety of pharmacoinvasive strategy following fibrinolysis for ST-elevation myocardial infarction (STEMI) in relation to renal function have not been established.

METHODS

Using patient-level data from 4 randomized controlled trials, we examined the efficacy and safety of pharmacoinvasive versus standard treatment after fibrinolysis for STEMI. Patients were stratified based on the estimated glomerular filtration rate (eGFR) on presentation (<60 mL/min/1.73 m² vs ≥60 mL/min/1.73 m²). The primary outcome was the composite of death or reinfarction at 30 days.

RESULTS

Of 2,029 patients, 457 (23%) had an eGFR<60 mL/min/1.73 m². Patients with eGFR<60 mL/min/1.73 m² were older and had higher Thrombolysis in Myocardial Infarction risk scores. Compared with patients with eGFR≥60 mL/min/1.73 m², patients with renal dysfunction had higher rates of the primary outcome (5.3% vs 11.8%, respectively; P<.001). There was no significant heterogeneity in the treatment effect of pharmacoinvasive strategy on the primary outcome (P heterogeneity=.73) or the rate of death or reinfarction at 1 year (P heterogeneity=.64) in relation to eGFR. Patients with renal dysfunction had higher rates of in-hospital major bleeding compared with patients with eGFR ≥60 mL/min/1.73 m² (7.7% vs 4.3%, respectively; P=.004); however, there was no difference in bleeding events between treatment arms in the overall cohort or in relation to eGFR (P heterogeneity=.67).

CONCLUSIONS

Renal impairment is associated with increased rates of adverse events in STEMI patients treated with fibrinolysis. However, the safety and efficacy of pharmacoinvasive strategy are preserved in patients with renal impairment on presentation.

Duration of dual antiplatelet therapy and associated outcomes following percutaneous coronary intervention for acute myocardial infarction: contemporary practice insights from the Canadian Observational Antiplatelet Study

Aims

There is a paucity of real-world, contemporary data of practice patterns and clinical outcomes following dual-antiplatelet therapy (DAPT) in acute myocardial infarction (AMI) patients treated with percutaneous coronary intervention (PCI).

Methods and results

The Canadian Observational Antiplatelet Study was a prospective, multicentre, cohort study examining adenosine diphosphate receptor antagonist use following PCI for AMI. We compared practice patterns, patient characteristics, and clinical outcomes in relation to DAPT duration (<6 weeks, 6 weeks to <6 months, 6 to <12, and ≥12 months). The primary outcome was the composite of non-fatal AMI, unplanned coronary revascularization, stent thrombosis, new or worsening heart failure, cardiogenic shock, or stroke. We identified 2034 patients with AMI treated with PCI. DAPT duration was <6 weeks in 5.2% of patients; 6 weeks to <6 months in 7.0%; 6 to <12 months in 12.6%; and ≥12 months in 75.3%. Patients who discontinued DAPT early had higher GRACE risk scores. Overall, mortality rate at 15 months was 2.5%. Compared with a duration of DAPT of ≥12 months, discontinuation of DAPT <6 weeks (P < 0.0001) and 6 weeks to <6 months (P = 0.02), but not 6 months to <12 months (P = 0.06), were independently associated with a higher incidence of the primary outcome among survivors.

Conclusion

One-in-four patients with AMI treated with PCI discontinued DAPT prior to the guideline-recommended 12-month duration. Patients in whom DAPT was discontinued early were at higher baseline risk and had higher rates of non-fatal ischaemic events during follow up.

Methodological Rigor in Preclinical Cardiovascular Studies: Targets to Enhance Reproducibility and Promote Research Translation

RATIONALE

Methodological sources of bias and suboptimal reporting contribute to irreproducibility in preclinical science and may negatively affect research translation. Randomization, blinding, sample size estimation, and considering sex as a biological variable are deemed crucial study design elements to maximize the quality and predictive value of preclinical experiments.

OBJECTIVE

To examine the prevalence and temporal patterns of recommended study design element implementation in preclinical cardiovascular research.

METHODS AND RESULTS

All articles published over a 10-year period in 5 leading cardiovascular journals were reviewed. Reports of in vivo experiments in nonhuman mammals describing pathophysiology, genetics, or therapeutic interventions relevant to specific cardiovascular disorders were identified. Data on study design and animal model use were collected. Citations at 60 months were additionally examined as a surrogate measure of research impact in a prespecified subset of studies, stratified by individual and cumulative study design elements. Of 28 636 articles screened, 3396 met inclusion criteria. Randomization was reported in 21.8%, blinding in 32.7%, and sample size estimation in 2.3%. Temporal and disease-specific analyses show that the implementation of these study design elements has overall not appreciably increased over the past decade, except in preclinical stroke research, which has uniquely demonstrated significant improvements in methodological rigor. In a subset of 1681 preclinical studies, randomization, blinding, sample size estimation, and inclusion of both sexes were not associated with increased citations at 60 months.

CONCLUSIONS

Methodological shortcomings are prevalent in preclinical cardiovascular research, have not substantially improved over the past 10 years, and may be overlooked when basing subsequent studies. Resultant risks of bias and threats to study validity have the potential to hinder progress in cardiovascular medicine as preclinical research often precedes and informs clinical trials. Stroke research quality has uniquely improved in recent years, warranting a closer examination for interventions to model in other cardiovascular fields.

Hyperglycaemia in comatose survivors of out-of-hospital cardiac arrest

BACKGROUND

The optimal blood glucose target during the early hospitalisation of comatose survivors of out-of-hospital cardiac arrest (OHCA) has not been established.

METHODS

In a retrospective cohort study, we examined clinical outcomes in relation to mean blood glucose during the first 96 hours of hospital admission in comatose survivors of OHCA with an initial shockable rhythm. Mean blood glucose was assessed as a continuous (primary analysis) and categorical variable: <6 mmol/L, 6 to <8 mmol/L and ⩾8 mmol/L. Co-primary outcomes were the rates of death during the index hospitalisation and severe neurological dysfunction at discharge. We used multivariable logistic regression analyses to adjust for baseline differences in patient and index event characteristics.

RESULTS

Among 122 eligible patients, death and severe neurological dysfunction occurred in 29 (24%) and 40 (33%) patients, respectively. Higher mean blood glucose levels during the first 96 hours of admission were associated with increased odds of death (odds ratio (OR): 1.50; 95% confidence interval (CI): 1.17-1.92; p = 0.001) and severe neurological dysfunction (OR: 1.42; 95% CI: 1.11-1.80; p = 0.004). The associations between mean blood glucose and the odds of death (OR: 1.35; 95% CI: 1.04-1.76; p = 0.02) and severe neurological dysfunction (OR: 1.28; 95% CI: 1.00-1.64; p = 0.05) persisted after adjusting for age, time from cardiac arrest to return of spontaneous circulation (ROSC) and vasoactive agent use. There was no interaction between age, time from cardiac arrest to ROSC or a history of diabetes mellitus and the relationship between mean blood glucose and co-primary outcomes.

CONCLUSIONS

In comatose survivors of OHCA with initial shockable rhythms, higher mean blood glucose levels during the first 96 hours of admission are associated with increased rates of death and severe neurological dysfunction.

Safety and Efficacy of Staged Percutaneous Coronary Intervention During Index Admission for ST-Elevation Myocardial Infarction With Multivessel Coronary Disease (Insights from the University of Ottawa Heart Institute STEMI Registry)

The optimal management strategy for patients with ST-elevation myocardial infarction (STEMI) and multivessel disease has not been well established. In the present cohort study, we sought to examine the safety and efficacy of inhospital staged PCI for patients with STEMI and multivessel disease. We identified all patients with STEMI referred for primary PCI who were found to have multivessel disease (stenosis ≥50% in nonculprit vessel) and compared clinical outcomes in relation to the management strategy, staged versus culprit-only PCI, for nonculprit vessel disease. The primary outcome was mortality at 180 days, and secondary outcomes included mortality during the index hospitalization and at 30 days, myocardial infarction, stent thrombosis, stroke, and bleeding. Of the 1,038 patients with STEMI meeting inclusion criteria, 259 (25%) underwent staged PCI and 779 (75%) culprit-only PCI during the index admission. Mortality at 180 days was 0.8% in patients with staged PCI and 5.0% in patients with culprit-only PCI (p = 0.003). The association between staged PCI and reduced mortality persisted after adjusting for baseline differences in patient characteristics and angiographic variables between the 2 cohorts (odds ratio 0.2, 95% confidence interval 0.04 to 0.77, p = 0.02). The rates of inhospital reinfarction in the staged and culprit-only PCI cohorts were 0.8% versus 1.3% (p = 0.50), respectively, stent thrombosis 0.8% versus 1.3% (p = 0.50), and stroke 0.4% versus 1.3% (p = 0.31). There were no inhospital adverse events related to acute occlusion of a nonculprit vessel in either cohort. Staged PCI during index admission is a safe and effective revascularization strategy for patients with STEMI and multivessel disease.

Efficacy and safety of a routine early invasive strategy in relation to time from symptom onset to fibrinolysis (a subgroup analysis of TRANSFER-AMI)

The aim of this study was to assess the efficacy and safety of an early invasive strategy post-fibrinolysis in relation to time from symptom onset to fibrinolysis in patients with ST-elevation myocardial infarction (STEMI). The Trial of Routine Angioplasty and Stenting after Fibrinolysis to Enhance Reperfusion in Acute Myocardial Infarction (TRANSFER-AMI) randomized 1,059 patients receiving fibrinolysis for STEMI to an early invasive strategy versus standard therapy. The primary end point was the composite of death, reinfarction, recurrent ischemia, new or worsening heart failure, or cardiogenic shock at 30 days. In this post hoc subgroup analysis, we examined the effect of an early invasive strategy on efficacy and safety outcomes after stratification by time from symptom onset to fibrinolysis (<2 or ≥2 hours). Of 1,059 patients in TRANSFER-AMI, 557 (53%) received fibrinolysis <2 hours and 502 (47%) ≥2 hours after symptom onset. Compared to patients who received fibrinolysis within 2 hours of symptoms, patients who received fibrinolysis ≥2 hours after symptom onset had higher Global Registry of Acute Coronary Events risk scores (median 127 vs 122, p = 0.004). The effect of an early invasive strategy did not differ between symptom-to-fibrinolysis time strata for the primary efficacy end point (p-heterogeneity = 0.67), 30-day mortality, the composite of death or reinfarction at 30 days, 6 months, or 1 year, or bleeding (all p-heterogeneity >0.40). In conclusion, the efficacy and safety of an early invasive strategy in patients undergoing fibrinolysis for STEMI do not vary in relation to time (<2 or ≥2 hours) from symptom onset to fibrinolysis.

A trabecular plate-like phenotype is overrepresented in Chinese-American versus Caucasian women

This study used extreme phenotype selection to define two trabecular bone phenotypes in a cohort of Chinese-American and Caucasian women. A trabecular plate-predominant phenotype is more common in Chinese-Americans while the rod-predominant phenotype is more typical of Caucasians. The robustness of these phenotypic associations with respect to lifestyle factors suggests that this trait may have a genetic basis and that these phenotypes can be utilized in future genetic studies.

INTRODUCTION

Compared to Caucasians, Chinese-Americans have more plate-like trabecular bone when measured by individual trabecula segmentation (ITS). These findings suggest a phenotypic difference between the races, which may be amenable to genetic analysis. We sought to identify a single ITS plate trait to pursue in genetic studies by conducting an extreme phenotype selection strategy to numerically define two distinct phenotypes-plate-like and rod-like-and determine whether the selected phenotypic associations were independent of lifestyle factors in order to conduct future genetic studies.

METHODS

A previously described cohort of 146 Chinese-American and Caucasian women with high-resolution peripheral quantitative computed tomography imaging and ITS analyses were studied with logistic regression and receiver operator characteristic analyses.

RESULTS

The tibial plate-to-rod (TPR) ratio was the best ITS discriminator of race. Using extreme phenotypic selection, two TPR ratio phenotypes were defined numerically: plate-like as a TPR ratio value in the highest quartile (≥1.336) and rod-like as a TPR ratio value in the lowest quartile (≤0.621). Women with a plate-like phenotype were 25.7 times more likely (95 % CI 7.3-90.1) to be Chinese-American than women with rod-like morphology. After controlling for constitutional and lifestyle covariates, women in the highest vs. lowest TPR ratio quartile were 85.0 times more likely (95 % CI 12.7-568.0) to be Chinese-American.

CONCLUSION

Using extreme phenotype selection, we defined a plate- and rod-like trabecular bone phenotype for the TPR ratio trait. The former phenotype is more common in Chinese-American women, while the latter is more typical of Caucasian women. The robustness of these phenotypic associations after controlling for differences in constitution and lifestyle suggest that the TPR ratio may have a genetic basis and that the extreme phenotypes defined in this analysis can be utilized for future studies.

Efficacy and safety of a routine early invasive strategy after fibrinolysis stratified by glycoprotein IIb/IIIa inhibitor use during percutaneous coronary intervention: a pre-specified subgroup analysis of the TRANSFER-AMI randomised controlled trial

OBJECTIVE

We evaluated the efficacy and safety of an early invasive strategy post-fibrinolysis in relation to glycoprotein (GP) IIb/IIIa inhibitor use.

METHODS

The Trial of Routine Angioplasty and Stenting after Fibrinolysis to Enhance Reperfusion in Acute Myocardial Infarction (TRANSFER-AMI) randomised 1059 ST elevation myocardial infarction patients to an early invasive strategy or standard therapy post-fibrinolysis. The primary end point was the composite of death, reinfarction, recurrent ischaemia, new or worsening heart failure, or cardiogenic shock at 30 days. In this pre-specified analysis, we examined efficacy and safety outcomes of an early invasive strategy after stratification by GPIIb/IIIa inhibitor use, which was permitted during percutaneous coronary intervention (PCI) at the discretion of the treating physician.

RESULTS

A total of 695 patients (65.6%) received GPIIb/IIIa inhibitors. There was significant heterogeneity (p<0.001) in the efficacy of an early invasive strategy compared to standard therapy, between the strata with GPIIb/IIIa inhibitor use (primary end point 9.6% vs 22.3% respectively, p<0.001) and without GPIIb/IIIa inhibitor use (primary end point 14.8% vs 10.4% respectively, p=0.21). Patients who received GPIIb/IIIa inhibitors had lower Global Registry of Acute Coronary Events (GRACE) risk scores compared to those without GPIIb/IIIa inhibitor use (median 121 vs 130, p<0.001). After adjusting for the interaction between GRACE risk score and treatment assignment, the heterogeneity in the efficacy of an early invasive strategy with respect to GPIIb/IIIa inhibitor use was no longer significant (p interaction=0.08).

CONCLUSIONS

The apparent difference in the efficacy of an early invasive strategy between GPIIb/IIIa inhibitor strata likely reflects an association between GPIIb/IIIa inhibitor use and baseline risk. GPIIb/IIIa inhibitor use during PCI at the discretion of the treating physician does not appear to modulate the efficacy of an early invasive strategy post-fibrinolysis.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov/ct2/show/NCT00164190, NCT00164190.

Combinatorial fluorescence energy transfer tags for multiplex biological assays

We report an approach for developing combinatorial fluorescence energy transfer (CFET) tags by tuning the tags' fluorescence emission signatures. The tags can all be excited at a single wavelength and analyzed by a simple optical system. We constructed eight CFET tags with unique fluorescence signatures, detected by a three-color capillary array electrophoresis (CAE) system with 488 nm excitation, using only three fluorescent dyes. A 1',2'-dideoxyribose phosphate spacer was used to separate the donor and acceptor to tune the energy transfer efficiency, generating unique fluorescence signatures. The spacer also served as an electrophoretic mobility tag to tune the mobility of CFET-labeled DNA for multiplex detection of single-nucleotide polymorphisms (SNPs). Six nucleotide variations were identified simultaneously using six CFET tags on synthetic DNA templates and on a PCR product from the retinoblastoma tumor suppressor gene.

A knowledge model for analysis and simulation of regulatory networks

MOTIVATION

In order to aid in hypothesis-driven experimental gene discovery, we are designing a computer application for the automatic retrieval of signal transduction data from electronic versions of scientific publications using natural language processing (NLP) techniques, as well as for visualizing and editing representations of regulatory systems. These systems describe both signal transduction and biochemical pathways within complex multicellular organisms, yeast, and bacteria. This computer application in turn requires the development of a domain-specific ontology, or knowledge model.

RESULTS

We introduce an ontological model for the representation of biological knowledge related to regulatory networks in vertebrates. We outline a taxonomy of the concepts, define their 'whole-to-part' relationships, describe the properties of major concepts, and outline a set of the most important axioms. The ontology is partially realized in a computer system designed to aid researchers in biology and medicine in visualizing and editing a representation of a signal transduction system.

Chromosome instability and immunodeficiency syndrome caused by mutations in a DNA methyltransferase gene

The recessive autosomal disorder known as ICF syndrome (for immunodeficiency, centromere instability and facial anomalies; Mendelian Inheritance in Man number 242860) is characterized by variable reductions in serum immunoglobulin levels which cause most ICF patients to succumb to infectious diseases before adulthood. Mild facial anomalies include hypertelorism, low-set ears, epicanthal folds and macroglossia. The cytogenetic abnormalities in lymphocytes are exuberant: juxtacentromeric heterochromatin is greatly elongated and thread-like in metaphase chromosomes, which is associated with the formation of complex multiradiate chromosomes. The same juxtacentromeric regions are subject to persistent interphase self-associations and are extruded into nuclear blebs or micronuclei. Abnormalities are largely confined to tracts of classical satellites 2 and 3 at juxtacentromeric regions of chromosomes 1, 9 and 16. Classical satellite DNA is normally heavily methylated at cytosine residues, but in ICF syndrome it is almost completely unmethylated in all tissues. ICF syndrome is the only genetic disorder known to involve constitutive abnormalities of genomic methylation patterns. Here we show that five unrelated ICF patients have mutations in both alleles of the gene that encodes DNA methyltransferase 3B (refs 5, 6). Cytosine methylation is essential for the organization and stabilization of a specific type of heterochromatin, and this methylation appears to be carried out by an enzyme specialized for the purpose.

Relationships between a new type IV secretion system and the icm/dot virulence system of Legionella pneumophila

We describe here a Legionella pneumophila type IV secretion system that is distinct from the previously described icm/dot system. This type IV secretion system contains 11 genes (lvh ) homologous to genes of other type IV secretion systems, arranged in a similar manner. The lvh genes were found to be located on a DNA island with a GC content higher than the L. pneumophila chromosome. In contrast to the icm/dot system that was shown to be required for intracellular growth in HL-60-derived human macrophages and Acanthamoeba castellanii, the lvh system was found to be dispensable for intracellular growth in these two hosts. The lvh system was found to be partially required for RSF1010 conjugation, a process that was previously shown to be completely dependent on several icm/dot genes. However, results obtained from analysis of double mutants in the icm/dot genes and the lvh genes revealed that lvh genes can substitute for some components of the icm/dot system for RSF1010 conjugation, but not for intracellular growth. These results indicate that components of the icm/dot system and components of the lvh type IV secretion system are able to interact with one another.